Question

If the briefcase hits the water 6.0 s later, what was the speed at which the helicopter was ascending?

Answer 1

Complete Question

In an action movie, the villain is rescued from the ocean by grabbing onto the ladder hanging from a helicopter. He is so intent on gripping the ladder that he lets go of his briefcase of counterfeit money when he is 130 m above the water. If the briefcase hits the water 6.0 s later, what was the speed at which the helicopter was ascending?

Answer:

The speed of the helicopter is $u = 7.73 \ m/s$

Explanation:

From the question we are told that

   The height at which he let go of the brief case is  h =  130 m  

    The  time taken before the the brief case hits the water is  t =  6 s

Generally the initial speed of the  briefcase (Which also the speed of the helicopter )before the man let go of it is  mathematically evaluated using kinematic equation as

      $s = h+ u t + 0.5 gt^2$

Here s  is the distance covered by the bag at sea level which is zero

      $0 = 130+ u * (6) + 0.5 * (-9.8) * (6)^2$

=>    $0 = 130+ u * (6) + 0.5 * (-9.8) * (6)^2$

=>   $u = \frac{-130 + (0.5 * 9.8 * 6^2) }{6}$

=>   $u = 7.73 \ m/s$